Australia's minister for Health, Aged Care and Sports, Sussan Ley, announced today she will step aside after it was revealed that she had used taxpayer-funded official trips for personal use, including one to buy herself an apartment.

Prime Minister Malcolm Turnbull said today he had asked for a thorough investigation into her travel claims and Ley "had agreed to stand aside without ministerial pay" until it is completed.

"I expect the highest standards from my ministers in all aspects of their conduct, and especially the expenditure of public money," Turnbull said in a statement.

Local media reported last week that Ley and her partner had bought an apartment worth A$795,000 (US$581,000) during a ministerial trip to the Gold Coast, a holiday destination in Queensland state and some 1,300km from her electorate, in May 2015.

Ley today said she had agreed to pay back some of the costs for her trips but maintained that she had not broken any rules.

"I am very confident that the investigations will demonstrate that no rules were broken whatsoever," she told reporters.

She said she visited the Gold Coast to have ongoing conversations with a health patient and her partner drew her attention to an auction during the trip.

The purchase "was neither planned nor anticipated," she said, adding she inspected the apartment for the first time ten minutes before the auction started and felt it "fit the bill".

"I realised that my purchase of the unit changed the character of the occasion to one of a more personal nature and I should have adjusted my (travel) claim accordingly."

Local media revealed that she had claimed travel costs to the Gold Coast for personal New Year's Eve celebrations two years in a row.

Ley, a parliamentarian since 2001, was appointed health minister in December 2014.

The controversy involving Ley is an embarrassing start to the year for embattled Turnbull.

Ley's spending inquiry follows a 2015 expenses scandal where a government MP was unseated after billing taxpayers for a helicopter flight and comes with Turnbull languishing in polls and facing a restive party room.

A Newspoll in today's Australian newspaper put Liberal prime minister Turnbull and his opposition Labour counterpart Bill Shorten as the least popular pair of national political leaders in 20 years.

In the year to come Turnbull's Liberal Party-led government faces a fractious Senate that has so far stymied major progress on its legislative agenda, mainly focused on spending cuts and tax reforms aimed at balancing the national budget.

Turnbull has also struggled to keep the support of the hard-right of his own party, which still simmers with resentment since he toppled the more conservative Tony Abbott as prime minister in a party-room coup in 2015.

- Agencies